1. Field of Invention
This invention relates to NFC enabled devices, and specifically to protecting NFC enabled devices from damaging voltages.
2. Related Art
Near field communications (NFC) requires that NFC devices be within a relatively small distance from one another so that their corresponding magnetic fields can exchange information. Ranges of up to several centimeters (generally a maximum of 1 meter) are common for NFC devices. Typically, a first NFC device transmits or generates a magnetic field modulated with the information, such as the credit information or the ticket fare information. This magnetic field inductively couples onto a second NFC device that is proximate to the first NFC device. The second NFC device may respond to the first NFC device by transmitting or generating its own modulated magnetic field and inductively coupling this magnetic field to the first NFC device. There are several standards in existence which set out certain communication protocols and functional requirements for NFC and other communications using the near field, such as ISO/IEC 14443, ISO 15693, ISO/IEC 18092 and ISO/IEC 21481.
A NFC enabled device is a type of NFC device that is capable of operating in an initiator mode to initiate a communication with another NFC enabled device and in a target mode to respond to the initiation of a communication by another NFC enabled device. The term “NFC enabled device” includes not only the NFC enabled device but also other initiator NFC enable devices, such as a RFID transceiver or reader that are capable of initiating a near field RF communication and/or a RFID transponder or tag that are capable of responding to initiation of a NFC by another NFC enabled device to provide some examples. Hence, the NFC enabled device can act as both a RFID transceiver and a RFID transponder and are able to communicate with other NFC enabled devices, RFID transceivers and RFID transponders.
In addition, NFC enabled devices may be associated with or comprised within or attached to certain peripheral devices, for example SIM cards (e.g. UICC), secure elements, memory devices (for example MCU, RAM, ROM and non-volatile memory), display driver or other drivers. During operation the NFC enabled device must also be able to communicate with and transfer data to and from such peripheral device.
Components of NFC enabled devices are generally protected from damaging voltages by voltage regulators such as shunt regulators. These regulators may have a finite response time during which components of the NFC enabled device are exposed to damaging voltages.
An aspect of the present invention provides a NFC enabled device that alleviates at least some of the aforementioned problems. Further aspects and advantages of the invention will become apparent from the detailed description that follows.
The invention will now be described with reference to the accompanying drawings. In the drawings, like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements. The drawing in which an element first appears is indicated by the leftmost digit(s) in the reference number.